【作者】 何丹；

【导师】 杨骏六；

【作者基本信息】 四川大学 ， 流体力学， 2005， 硕士

【摘要】 由于城市现代化和工业发展,城市生活废水和工业污水都逐渐增多。避免环境被污水污染成为环境保护的一个越来越重要的方面。水污染防治一方面需要研究高效的污水处理方法,另一方面需要有效地控制污水向环境的排放。 过去人们多采用实践的方式来控制污水的排放,比如,到实际环境中测量水质,与标准水质相比较,再反过来限制,调整污水排放量。这类方法虽然切实可行,但是开销较大。当前,随着计算流体力学的发展,污水排放过程和污染物的浓度分布已可以由数值模拟得到。使用数值模拟的方法,在实际现场测量之前,对污水在受纳水体中的扩散便可以掌握其大致情况。这有助于减少实际测量的花费,使得污水排放的控制更加方便。 作为污水排放数值模拟的典型问题,河道岸边侧向排放得到了广泛的研究,污水岸边排放属于典型的对流传质问题,且在现实情况下极大可能是湍流问题,故湍流模型的选取在数值模拟中起着重要的作用。在目前多数研究中,采用的湍流模型为标准k-ε湍流模型,这种模型虽已被证实是一种适应范围较大的模型,但其并不适用于流体中雷诺正应力占重要作用的情况,目前所知,具有回流区和二次流的一些流动便属于此种情况。为了使数值模拟能够更加适应真实条件,本文采用了一种更优越的湍流模型,非线性k-ε模型进行计算。同时,采用有限体积法将控制微分方程离散为代数方程,采用SIMPLE方法求解压力。最后,得到了合理的数值计算结果,并与实验数据和标准k-ε模型的计算结果进行了对比。更多还原

【Abstract】 The wastewater from the city residences and the industry facilities gets more and more these year because of the city modernization and the industry development. Thus, preventing environment from being polluted by wastewater gets to be a more and more important aspect of environment protection. In order to do this, the problem on one hand, is to study about the efficient ways to treat the wastewater, and on another, is to effectively regulate the amount of wastewater’s discharging to environment.In the past, people used to control the discharge of wastewater in the practical ways, for example, measure the water quality of receiving environment, check it with the criterion, and then come back to control the discharging amount. This kind of methods is practical, but it’s holding fairly large spending. Nowadays, with the development of computational fluid dynamics, the procedure of wastewater discharge and the concentration distribution of the waste could be easily got by numerical simulation. By this means, a general idea about the diffusion of wastewater in the receiving waters can be got before the actual measurement, which helps to cut down the measurement spending and makes the regulation of wastewater discharge more convenient.As a typical case in the field of numerical simulation to the wastewater discharge, the problem of side discharge into a river is widely studied by researchers. It is a problem of convection mass transfer and could be most probably a problem ofturbulence in real condition, so the turbulence model acts an important role in the numerical simulation. In most cases in current researches, the standard k - ε turbulence model is adopted. Although the standard k-ε turbulence model has been proved to be a model adapting a large range of conditions, it does not fit in with the cases where the normal Reynold stress of fluid is of great importance. As generally known, these cases include at least some cases where recirculation or secondary flow takes place. In order to make the simulation adaptive in a greater degree to the real conditions, in this dissertation a more superior turbulence model known as nonlinear k-ε model is adopted for calculation. The finite volume method is used to transform the controlling differential equations into the algebra ones, and the semi-implicit method for pressure-linked equations (SIMPLE) is used to solve the pressure. A reasonable numerical simulation result is got, and then is compared with the experimental data as well as the result got by using standard k-ε model.更多还原